The invention relates to machinery for reducing waste wood, such as demolition debris, pallets, ties, large timbers, old lumber, stumps, brush, dead trees, and the like to particulates which are useful, for example, as mulch ground cover.
The machines widely used today for reducing such waste wood and like waste products are the tub grinder with its hammer mill underlying the floor opening in the tub, and the so-called force feed horizontal machines frequently referenced as xe2x80x9cwood hogsxe2x80x9d in which a swingably mounted feed roll cooperates with an underlying chain conveyor to feed waste wood to a rotary drum having reducing comminuters or hammers on its periphery.
In the past, hammer blocks, having forwardly projecting, spaced apart radially inner and outer elongate, carbide coated tooth edges have been used to fragment waste wood. The blocks can be rotated 180xc2x0 to reposition the less rapidly wearing radially inner edge as the outer tooth edge, after the appearance of a certain amount of wear on the original outer edge. Such hammer blocks require quite frequent replacement, with the machines expensively in a xe2x80x9cdownxe2x80x9d condition while the replacement is taking place. Moreover, the fragments produced by such toothed hammer blocks are of a somewhat bulky character. Also, on the market are conical tooth comminuting members mounted on support members which have no tooth edges. While such conical tooth members operate well to fragment wood products, they also tend to produce a relatively coarse or bulky product.
The present invention relates to a new concept involving marrying the conical tooth to a hammer knife block having at least one forwardly protruding axially extending tooth edge which cooperates with the conical tooth to produce a better product for use as a mulching agent. The hammer assembly of the invention produces more completely shredded, thinner, feathery looking fragments in a consistent manner. The conical or generally bullet-shaped projecting tooth of the new assembly first engages the wood piece to tend to impale it, and then tear it, and the torn piece is then immediately reduced further by the tooth edge or edges which follow closely behind the conical tooth. The forwardly projecting conical tooth further protects the hammer assembly in the sense that the edge or edges of the tooth or teeth wear less rapidly then previously. Moreover the conical tooth or teeth involved in the invention may incorporate a bolt-like member which secures the knife assembly in position on its hammer shoe.
One of the prime objects of the invention is to provide a hammer assembly which will operate to shred a more desirable mulching product in a very efficient and rapid manner.
Another object of the invention is to provide a hammer assembly having an extended effective service life, and which, when required, can be readily and rapidly adjusted or replaced.
A further object of the invention is to provide a hammer assembly which operates extremely effectively in tub grinders and wood hogs, particularly, and greatly improves the overall operation of these machines.
Other objects and advantages of the invention will become apparent with reference to the accompanying drawings and the accompanying descriptive matter.